It is not too surprising that new to LEAF owners are confused by people who say charging to below 100% SoC is advisable, yet Nissan does not give the owner that option, implying that routine charging to 100% SoC is fine.
Answer: Nissan is wrong if the goal is to mitigate battery degradation. How wrong depends on the circumstances. The longer the car sits at 100% SoC, and in particular the longer the car sits at 100% SoC when the battery is hot, the worse the Nissan approach becomes.
OP: you will find that EVERY single owner in this forum who wants to slow down battery degradation takes steps of one form or another to do two things: reduce the time the pack sits at 100% SoC; and second, tries to charge after the pack has had a chance to cool down some in the hot months of the year. The actual implementation details vary from person to person because each person uses their car differently, and each person has their own inconvenience:benefit threshold.
Read the different approaches and adapt one to fit you. Follows is my personal advice to you:
Don't let perfect stop you from doing good enough
A battery stewing for an hour or two is a whole lot better than overnight
A battery stewing at 95% SoC or less is a whole lot better than stewing at 100%
A battery stewing at 80F is a whole lot better than stewing at 90F+
Make an effort, and get on with life. The car will thank you. You can probably gain 70 - 80% of the possible benefit by doing 15 - 25% of the optimal.
2013 LEAF 'S' Model with QC & rear-view camera
Bought Jan 2017 from N. Cal
Two years in Colorado, now in NM
03/18: 58 Ahr @28k miles. 10/21: 53.4 Ahr @ 40k miles
2018 Tesla Model 3 LR, Delivered 6/2018. Sold 11/2021, awaiting Tesla Model Y